Download Project 5 - University of Cincinnati

PROJECT SUMMARY REPORT
Separated Flow Control in Low-Pressure Turbines and
Automobiles
Submitted To
The 2012 Academic Year NSF AY-REU Program
Part of
NSF Type 1 STEP Grant
Sponsored By
The National Science Foundation
Grant ID No.: DUE-0756921
College of Engineering and Applied Science
University of Cincinnati
Cincinnati, Ohio
Prepared By
Michael Cline, Junior, Mechanical Engineering, School of Dynamic Systems
Brandon Mullen, Sophomore, Aerospace Engineering, School of Aerospace Systems
Report Reviewed By:
Dr. Kirti Ghia
REU Faculty Mentor
Professor
School of Aerospace Systems
University of Cincinnati
September 17 – December 6, 2012
Goals and Objectives
Goals
1. Overall
a. Develop a working knowledge of flow separation and flow control strategies.
2. Low-Pressure Turbine Application
a. Delay or annihilate flow separation on an NACA0012 airfoil computational fluid dynamics (CFD)
simulation as predicted.
b. Generate original data to expand body of knowledge of active control strategies for flow separation.
3. Automobile Application
a. Understand what current vehicle manufactures are doing to implement flow control strategies, if
any.
b. Develop active control strategies for flow past an automobile and predict using CFD software.
Objectives
1. Overall
a. Perform literature review for unique applications/aspects to investigate.
b. Develop proper implementation methods and equations for CFD simulation in ANSYS’ Fluent and
Gambit software.
c. Successfully simulate and prevent low-speed flow separation.
d. Generate data on flow control strategies and compile in the form of an AIAA meetings paper and
possibly publish in a journal.
2. Low-Pressure Turbine Application
a. Learn how to implement plasma actuator using electric field equations to develop an active control
strategy.
b. Expand upon current knowledge of ANSYS CFD software to perform more complex simulations.
3. Automobile Application
a. Gain working knowledge of ANSYS CFD suite.
b. If possible, develop an active control strategy for automobiles.
Tasks Undertaken
Low-Pressure Turbine Application
1. Literature review of plasma actuator control studies to determine control implementation on airfoil
and equations necessary for implementation.
2. Replication of prior study by Shyy et al in 2002. This was a simple study of plasma actuator
effect on flow over a flat plate.
 Replicated their simulation geometry and mesh.
 Generated functions to simulate plasma actuator effect on flow.
 Ran simulation using derived functions and variables.
 Compared simulation results with Shyy et al’s results.
 Considered implementation method validated with agreement of results within 14%.
3. Generated mesh using NACA0012 airfoil and implementation of plasma actuator geometry from
Shyy et al comparison.
4. Ran simulation using functions derived from the Shyy et al comparison, modified to apply to airfoil
geometry.
Automobile Application
An extensive literature review encompassed the first three to five weeks. Brandon needed a firm
understanding of the principle of separated air-flow before progressing towards modeling control
techniques on automobiles. A conceptual understanding was established with an introduction into the
quantitative approach. Understanding of differential equations is needed in complete quantitative
comprehension. Also, a search was conducted for current examples of control techniques implemented
by automobile manufactures. Significant research had been done by Dr. V.J. Modi of the University of
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British-Columbia on Moving Surface Boundary Layer Controls (MSBC) implemented on tractor-trailers.
This research served as a basis for the current work under investigation.
CFD simulations included:
1. Baseline (no separation control)
2. MSBC cylinder application at rotational velocities of:
a. 0 rpms
b. 101 rpms
c. 203 rpms
d. 305 rpms
e. 406 rpms
f. 508 rpms
g. 610 rpms
Results
Low-Pressure Turbine Application
1. Completely eliminated flow separation over NACA0012 airfoil with plasma actuation using values
derived from Shyy et al. study (Voltage = 4000 V and A/C Frequency = 3000 Hz).
2. Modified voltage and frequency supplied to the actuator to discern minimum voltage and frequency
for optimum separation control.
a. Minimum voltage 60% that of Shyy et al (2400 V).
b. Minimum frequency 25% that of Shyy et al (750 V).
Automobile Application
1. Reduced flow separation seen with application of MSBC cylinder on car model. Separation wake
decreased as linear surface velocity of cylinder increased.
a. Application of cylinder with no rotation yielded some decrease in flow separation.
b. Efficient reduction seen at surface velocity of 610 rpm’s. Increases in rotational speed
yielded small to no decrease in separation wake for input.
Conclusions
1. Overall
a. We were able to develop a working knowledge of flow separation and flow control strategies.
b. We were able to reduce or eliminate flow separation in targeted areas, thereby decreasing drag
and increasing efficiency of the blade or automobile.
2. Low-Pressure Turbine Application
a. The voltage and frequency of the actuator could be cut by 40% and 75% respectively and still
reduce flow separation by about 90%. This gives the actuator flexibility that makes it appealing
for implementation in industry.
3. Automobile Application
a. MSBC cylinders are effective at relatively low rpm’s. This heightens the appeal of MSBC cylinders
on industrial applications.
Training Received
Received further instruction in ANSYS suite computational fluid dynamics programs Gambit and Fluent.
 Learned how to implement User-Defined Functions in Fluent.
 Learned how to use fluid Profile Files in Fluent.
 Learned how to define a relative velocity boundary condition for a “Wall” in Gambit and Fluent.
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